Pelletising apparatus

ABSTRACT

Apparatus for pelletising material of low binding power or low moisture content includes a conveyor, a spreading and compressing device, and breaking means. The material is fed onto the conveyor belt which in cooperation with the spreading and compressing device forms the material into a layer. As the material travels along on the conveyor belt it is subjected to heat exchange for solidifying the layer. Subsequently the layer is broken up into pellets.

United States Patent Eirich et a].

1 1 Oct. 17, 1972 [54] PELLETISING APPARATUS 3,119,146 1/1964 Crandall et al ..18/1 8 l72| inventors: Wilhelm Eirich, Waldurner Str. 41; D

Gustav Eirich, Bahnhofstr. 19, both Prlmary P' oi Hardheim. Nordbaden. Germany A!! neyMcGlew and Toren |22| Filed; July 27, 1970 [57] ABSTRACT [2]] Appl s8433 Apparatus for pelletising material of low binding power or low moisture content includes a conveyor, a [30] Foreign Application Priori y Dill! spreading and compressing device, and breaking Aug 6,1969 Switzerland 1193669 means. The material is fed onto the conveyor belt which in cooperation with the spreading and com- [52] US. Cl. ..18/] B p device forms the material into a y AS the 511 int. Cl ..B29b 1/02, 82% 5/00 material travels along on the conveyor belt it is [58] Field of Search ..18/1 B, 4 B, 5 A jected to heat exchange for solidifying the layer. Subsequently the layer is broken up into pellets. 56 R f rences Cited 1 e e 19 Claims, 9 Drawing Figures UNITED STATES PATENTS 2,867,843 1/1959 Browne et a1. ..18/1 B m minncr 1 1 m2 MEIZUFS F/GT 3 WVENI'O/P WILHELH Efihcu cusm Emma PAIENTEU um 17 1972 SHEU 3 0f 5 W n/rap lLHELh 5m H GusTnv m PAIENTEnnm 1? 1912 3.6 98 842 sum 5 or 5 wrm/rop wmusm Emu GUsTRV Efiucu N 1%? K Tm Maw PELLETISING APPARATUS The production of pellets or granulates from linegrained material is gaining more and more importance in many branches of industry. The most common method is to pelletize by the rolling down method, using inclined plates, pelletizing drums or mixing granulators with a horizontal plate. The pelletizing process is generally perfectly successful if the material to be processed is in a sufficiently dry, free-running state and contains a sufficiently high proportion of very fine granular materials, and if the conditions for adequate cohesion are provided by moistening. However, the widely used and wellproven pelletizing machines cannot always be employed. They have been found to be unsuitable as soon as one has to pelletize material containing a high proportion of sand and additives which have only slight binding power or cohesion. Furthermore, pelletizing with the said machines entails adding wetting fluid which has to be removed after the pellet formation, together with the inherent moisture content of the starting materials, by drying the pellets. The drying process is expensive and has an unfavorable effect on the cost of the pellets. An example which might be cited in this connection is the pelletizing of clay, which has good inherent cohesion, but which requires not insignificant quantities of wetting fluid in order to form pellets; the fluid then has to be removed in a subsequent drying process at considerable cost. For the building industry, the availability of artificial gravel is increasing in importance. Here the known machines set cost limits which prevent any decisive breakthrough to the use of artificial gravel.

The problem underlying the present invention is to avoid these defects, and the invention provides apparatus for pelletizing material with low binding power and/or low moisture content comprising a conveyor, means for spreading the material to be pelletized over the conveyor to form a layer and for compressing the layer, and breaking means to divide the layer into pellets. The apparatus is particularly suitable for producing artificial gravel, consisting of light aggregates which are mixed with a hydraulic binder, such as cement or lime, and then hardened together in a steam autoclave by the sand-line brick method, for the apparatus provides preshaped and hardened structures which do not have to be produced under difficult conditions by the rolling down process used in known machines.

One embodiment of the invention is characterized in that devices inter-acting with the conveyor are provided to convey a temperature-controlling medium. This embodiment is particularly suitable for pelletizing materials with poor inherent cohesion. The construction is also suitable for pelletizing clay, the constituents of which have good inherent cohesion. But since only a small quantity of wetting fluid has to be added here as compared with known apparatus, and since the fluid is carried away by the temperature-controlling medium following the shaping of the pellets, the pelletizing of clay becomes particularly economical.

The conveyor may comprise a conveyor belt circulating endlessly around rollers, with supporting members arranged below the upper run and extending transversely to the direction of movement of the belt. In conjunction with other features yet to be mentioned, this construction makes possible continuous compression and thus uninterrupted output of shaped pellets. in

another form of the invention the conveyor comprises a revolving disc with a feed point, a distributor, compressing means and a deflector arranged in front of the feed point to break up the compressed layer. It may be appropriate to have the conveyor in the form of a revolving disc when the apparatus according to the invention has to be included in existing installations which are laid out so as not to allow for the inclusion of conveyors in the form of an endless circulating belt.

In a further form of the invention, the compressing means take the form of a roller arranged above the upper run of the conveyor belt, working together with the conveyor belt and a supporting member and forming a drawing in gap or nip. This embodiment is desirable if the material to be pelletized has to undergo relatively brief compression.

The device for conveying a temperature-controlling medium may be in the form of a hood covering the upper run with an inlet and an outlet to convey a gaseous temperature-controlling medium. This has the advantage that the material compressed into a layer is brought into heat exchange with the temperature-controlling medium, so that the small quantity of wetting fluid used in the apparatus according to the invention can be removed rapidly.

The device for conveying a temperature-controlling medium may be in the form of hollow bodies arranged below the upper run and between the supporting members, through which liquid media can be passed. This construction is particularly suitable if the layer is to be heated additionally for quick removal of the wetting fluid. It will be obvious to an expert that the hollow bodies can be fitted not only to convey liquid media but that they are also suitable to convey media in a gaseous state. It is further possible for the individual components of the device for conveying a temperature-controlling medium to be fed with media of a differing heat content, provided that a covering hood, as well as ho]- low bodies, is provided on the apparatus according to the invention.

An appropriate means of dividing the compressed layer into pellets is a breaker in the form of a roller arranged above the upper run; it may have projections at its outer periphery to impress in the layer a pattern corresponding to the size of the pellets to be produced.

The production of artificial gravel, for example, requires a longer lasting and stronger compacting pressure, so it is desirable to design the apparatus with the compressing means comprising a backing plate arranged below the upper run, and a pressure plate provided above the upper run and adapted to be raised and lowered, with a vibrator.

In one embodiment of the invention the pressure plate with the vibrator is designed to move in and contrary to the direction of movement of the upper run of the conveyor belt; this helps to remove air from the material.

In a further embodiment the pressure plate is designed to convey a temperature-controlling medium, which heats the pressure plate for the purpose of facilitating its release from the strip of pressed material.

In order to reduce the adhesion between the top of the backing plate and the underside of the upper run, the backing plate may contain nozzles fed with compressed air to maintain an air cushion between itself and the underside of the upper run of the conveyor belt.

In many cases it is desirable for the breaker to be in the form of a cutter which can be raised and lowered relative to the top of the upper run and which carries a compressible stripper near its cutting edge. At the beginning of the raising movement the cutter is first released from the strip of compressed material, while the compressed stripper still remains in contact therewith. This prevents the top layer of the strip from being pulled off, as might happen when processing materials with poor inherent cohesion.

In a further advantageous form of the invention the backing plate has two heatable guide plates laterally bounding the conveyor belt. This has the advantage that the strip of compressed material is laterally bounded during compression, so that a strip with a sharp outline is formed.

In order to make a strip of uniform thickness it is important for the material on the conveyor belt to be distributed evenly prior to compression. For this purpose, a rotating circular brush may be provided in front of the compressing means in the direction of movement of the conveyor belt, to spread the material evenly over the belt.

In the production of phosphoric acid, ground crude phosphate is used, which is processed into granulates in inclined plate granulators or like granulating devices operating on the rolling down principle, with binders and a high moisture content being added. After the formation of the granulates the moisture content has to be removed by applying a large amount of heat. At the same time the size and strength of the granulates obtained leave much to be desired. In an embodiment of the invention suitable to produce crude phosphate mouldings which do not have these drawbacks the compressing means comprise a rammer driven by a working medium, with a foot corresponding to the width of the conveyor belt, and an endless belt which moves around the rammer and foot and is guided around rollers. This embodiment is advantageously constructed with the endless belt biased, near and on both sides of the foot, towards the top of the upper run of the conveyor belt by means of rollers and springs. In order to make crude phosphate mouldings it is advisable to provide the top of the endless conveyor belt with projections. This construction of the conveyor belt is obviously also suitable to make mouldings of materials other than crude phosphate.

Preferred embodiments of the invention will now be described, with reference to the accompanying drawings. In the drawings:

FIG. I is a side elevation of one embodiment of the apparatus according to the invention;

FIG. 2 is a view of the FIG. 1 apparatus swivelled through 90 and omitting the mixing and distributing means;

FIG. 3 shows a first modified embodiment of the invention;

FIG. 4 is a side elevation of the FIG. 3 embodiment;

FIG. 5 shows an embodiment without any hood engaging over the conveyor to carry a gaseous medium, and with a roller as a component of the compressing means;

FIG. 6 is a side elevation of FIG. 5;

FIG. 7 shows an apparatus similar to that in FIG. 5 with a pressure plate as part of the compressing means;

FIG. 8 shows an apparatus similar to FIG. 7 with a modified compressing means; and

FIG. 9 is a side view of FIG. 8.

FIG. 1 shows a mixer 1, below which there is a distributing means 2, which conveys material onto the apparatus according to the invention with the aid of deflecting plate 3. The mixer and distributing means are not part of the invention and will consequently not be explained in detail.

The apparatus according to the invention comprises a conveyor 4, a device for conveying a temperaturecontrolling medium 5, a breaker 6 in the form of a roller, and a compressing means 17. The conveyor 4 consists of a belt 8 moving around rollers 7, and below the upper run of the conveyor belt 8, supporting members 9 in the form of rollers are mounted with their shafts extending at right-angles to the direction of movement of the belt 8. This provides a fairly strong support for the conveyor belt 8 and, as shown in FIG. 1, a compressing means 17 is provided above the upper run of the endless belt, near the distributing device 2 and deflecting plate 3; the compressing means 17 are in the form of a roller which forms the drawing-in gap or nip together with the supporting rollers 9 and the conveyor belt 8, so that the loosely poured-on material is spread into a layer and compressed. In the present case the compressing means is shown as a roller. However, the invention is not restricted to this embodiment, and instead of a roller a pressure plate with a vibrator may be used, working together with a backing plate.

As shown in FIGS. I and 2, the endless conveyor belt runs through below a hood 18 which is a component of the device for conveying a temperature-controlling medium. The hood 18 contains an inlet 19 and two outlets 20 to pass through a gaseous temperature-com trolling medium, and is constructed so that it also covers the compressing means 17 and the breaker 6 in the form of a roller. Below the upper run and between individual supporting rollers 9 there are hollow bodies through which, for example, a coolant or steam can be passed. If the material has to be subjected to intensive heat treatment, the hood l8 and hollow bodies 2i may be kept in operation simultaneously. If no strong heat action is desired, one of the two arrangements has to be shut down.

FIG. 3 shows a modified embodiment of the apparatus according to the invention, which differs from that described above in that the endless conveyor belt 8 here takes the form of a revolving disc 10. 11 is a feed point where the material is placed on the disc, and a distributor l2 ensures that the material is spread evenly over the whole radius of the disc. A compressing means 13 in the form of a roller compacts the material, which is then passed to a deflector 14 arranged above the disc 10, which breaks the material and removes it from the disc. The deflector 14 is here shown as a stationary sheet of metal, although it could be replaced by a roller breaker.

FIG. 4 is a side view of the FIG. 3 embodiment, and this Figure clearly shows that the revolving disc 10 is in the form of a hollow body with flow chambers 22, through which a temperature-controlling medium can be passed for heat exchange with the material on the disc. The temperature-controlling medium can be introduced into the disc through a connecting piece 16 and is discharged from the disc through a further connecting piece 23. FIG. 4 shows a heat source 15, and the circuit of the temperature-controlling medium is indicated in broken lines. The heat source may be a refrigerator or, for example, a steam generator, depending on the material to be treated.

In the above, the breaker 6 has been described as being in the form of a roller. This roller may have a smooth surface, but in many cases it is desirable to provide the smooth surface with projecting ribs which impress a pattern in the layer of material, so that the layer falls apart in pieces of predetermined size, when broken up, The dividing of the layer into smaller pieces is facilitated by the fact that the upper run of the endless conveyor belt is slightly deflected from its horizontal position, whereby a bending stress is exerted on the layer, making is easier to break.

FIG. 5 shows an apparatus according to the invention constructed similarly to that in FIG. 1. For reasons of clarity like components carry like references. The conveyor 4 comprises an endless belt 8 running around rollers 7. Supporting members 9 in the form of rollers are provided inter alia below the upper run of the endless conveyor belt 8. As shown in the Figure, parts of the device for conveying a temperature-controlling medium are located between the supporting members 9, namely hollow bodies which have already been referred to above as cooling bodies 21. As already mentioned, the term cooling bodies" does not exclude the possibility of passing a heating medium through them. Above the upper run of the belt 8 is a strip 24 of compressed material running from the compressing means 17 to the delivery end of the belt 8. In contrast with the compressing means in FIG. 1, these means comprise a roller 25 co-operating with a backing plate 26. The backing plate 26 is provided with nozzles 27 which can be fed with a flow medium such as air, so that an air pocket is formed between the top of the backing plate 26 and the underside of the upper run of the endless conveyor belt 8 to reduce the friction between the corresponding surfaces of the said parts. FIGS. 5 and 6 clearly show that the backing plate 26 has lateral guide plates 28 between which the upper run of the belt 8 passes. The plates 28 are interconnected by a wall (not shown in detail) extending transversely of the belt 8 to form a conveying funnel 29 at the feed end of the conveyor. Thus a laterally bounded space is formed for the roller 25, in which it can come into action. Here it should be mentioned that there is a possibility of the roller being constructed as a hollow cylinder for the purpose of being heated; this may be advantageous for special materials to be compressed, e.g. to make it easier to lift the roller 25 off the surface of the strip 24 of compressed material. There is also a possibility of making the guide plates 28 in the form of hollow bodies through which a temperature-controlling medium can be passed. Operating between the funnel 29 and the compressing means 17 is a circular brush 30 which can be driven to perform a rotary movement; the brush acts between the guide plates 28 and distributes the material evenly over the width of the conveyor belt 8. The roller 25 may be free-running although it is also possible for it to be driven. A vibrator 31 is provided to reinforce the compressing action of the roller 25. After the compressing means in the direction of movement of the conveyor belt 8 is a corrugating or cutting means 32, comprising a cutter 33 with a compressible stripper 34 attached to it. The cutter 33 forms the notches, shown in FIGS. 5 and 6, in the strip 24 of compressed material, and the compressible stripper 34 is arranged on the cutter 33 in such a way that when the notch has been made the cutter 33 if first disengaged from it before the stripper 34 is lifted off the top of the strip 24. The cutting means 32 can be controlled so as to maintain a particular spacing between the notches, so that the strip 24 can be divided into pieces of equal size.

FIG. 7 shows an apparatus similar to that in FIG. 5. Except for the compressing means 17, the above specific description also refers to this embodiment, so will not be repeated. Instead of the roller 25 described above, the compressing means 17 here has a pressure plate 35 with a vibrator 36 mounted on it. The pressure plate 35 works together with the backing plate 26 already described. The plate 35 may be shaped as a hollow body through which a temperature-controlling medium can pass.

A special feature of this embodiment is that the pressure plate 35 is constructed so that it can move partly in the direction of movement of the conveyor belt 8, as indicated by the dash and dot lines in FIG. 7; in this way, a lasting compressing effect can be obtained, thus also helping to insure that the air contained in the material can escape. When the plate 35 has reached the final dash and dot position in FIG. 7, it is raised, moved in the opposite direction to the conveyor belt 8, and moved in a downward direction to apply pressure to the material. Thus it moves along a rectangular path.

In the embodiment described, the compressing means, thermal devices and breaking means have always been described an interacting with an endless conveyor belt. However, it is possible to depart from this constructional principle; for example, compression and distribution may be carried out in conjunction with a circulating rubber conveyor belt and the strip of material formed can then be passed onto a metal chain belt, the links of which may be exposed to a temperature-controlling medium. This embodiment may be preferable if special heat-applying conditions should be necessary to form the pellets, such as might have a harmful effect on a rubber-like endless conveyor belt.

FIG. 8 shows an embodiment similar to that in FIG. 7 and particularly suitable inter alia for producing crude phosphate mouldings. The only difference between this embodiment and FIG. 7 is the construction of the compressing means 17. The other parts of the apparatus, except for the conveyor belt 8, are similar to that in FIG. 7, so will not be described again. The compressing means 17 comprise a rammer 37 driven with a working medium, for example, drivable with compressed air, and provided with a foot which, as indicated in FIG. 9, has the same width as the conveyor belt 8 and also operates between guide plates 28 which can be heated. An endless belt 39 runs around the rammer about rollers 40, so that a compression chamber, bounded on all sides, is formed between the top of the upper run, the side walls of the guide plates 28 and the underside of the belt 39. The working face of the foot 38 acts on the surface of the belt 39. The belt 39 runs at the same speed as the conveyor belt 8 and fulfils two functions: it firstly serves to reduce clatter, and a further function is to form mouldings with a flawless surface. At the foot 38 and between the two rollers 40 are rollers 41 which, as shown most clearly in FIG. 8, are biased by springs so that the belt is urged against the layer of material by spring force. The roller 41, which is in front of the foot 38 in the direction of movement of the conveyor belt 8, may be biased with a spring 42 having a stronger bias, since this roller exerts a precompressing action. The roller which is behind the foot 38 in the direction of movement of the belt 8 will obviously undergo greater vertical deflection than the roller 41 in front of the foot 38. As crude phosphate mouldings in particular must have a special thickness, it is particularly desirable to provide the top of the endless belt 8 with projections 43, so that notches can be made in the strip 24 of the compressed material not only by the cutter 33 but also by the projections 43, thereby facilitating the separation of the individual mouldings from one another at the end of the belt. Furthermore, the projections 43 give the mouldings an initial velocity at the end of the endless conveyor belt which helps to accelerate their removal.

The mode of operation of the apparatus according to the invention will be explained only in connection with FIGS. 1 and 3, since with a knowledge of this the operation of the modified embodiments will be obvious. Material mixed in the mixer 1 is passed to the distributor 2 which places it on the conveyor belt 8 with the aid of the sheet metal guide. Owing to the fact that the compressing means 17 forms a nip together with the conveyor belt 8 and a supporting roller 9, the loosely poured-on material is spread over the width of the conveyor belt, to be shaped simultaneously into a layer on passing through the nip. The material thereupon advances on the conveyor belt and undergoes heat exchange with the temperature-controlling medium, whereby the layer of material is further consolidated. The components of the layer of material now have adequate cohesion, so that pellets are formed during the breaking process and can be passed on for further processing. The modified apparatus in FIG. 3 operates in the same way. Material is poured onto the disc 10 at the feed point 11, and the distributor 12 carries out radial distribution of the poured-on material before it passes through the gap between the compressing means 13 and the disc 10. The resultant layer undergoes heat exchange, since the temperature-controlling medium is constantly circulating through the disc 10 from the heat source l5. After suitable compacting the layer is broken into pellets by the deflector and simultaneously conveyed radially outwards.

The advantage of the apparatus according to the invention is that pellets can be formed with it which could not have been produced in conventional machines using the same materials. The apparatus saves processing, for it does not require any finely ground starting materials. Thus, ores, batch, washed sands and similar materials which are not very finely ground can be pelletized. The apparatus also requires smaller quantities of wetting fluid than before, so that great economies in drying are possible.

We claim:

1. Apparatus for pelletizing material of low binding power or low moisture content, comprising a conveyor for transporting said material from a charging point to a discharging point, means for spreading the material to be pelletized over the conveyor to form a layer, means for compressing the material layer, and breaking means located downstream from said compressing means for dividing said layer into pellets, said compressing means and said breaking means being separately positioned along said conveyor at spaced apart points and extending at least to points intermediate said charging and discharging points.

2. Apparatus according to claim 1, wherein a device co-operating with the conveyor is provided to convey a temperature-controlling medium.

3. Apparatus according to claim 1, wherein the conveyor comprises a conveyor belt circulating endlessly about rollers, with supporting members arranged below the upper run and extending transversely to the direction of movement of the belt.

4. Apparatus according to claim I, wherein the conveyor comprises a revolving disc, with a feed point, a distributor, compressing means and a deflector arranged in front of the feed point to break up the compressed layer.

5. Apparatus according to claim 1, wherein the compressing means is in the form of a roller arranged above the upper run of a conveyor belt, inter-acting with the belt and a supporting member and forming a nip.

6. Apparatus according to claim 2, wherein the device for conveying a temperature-controlling medium is constructed as a hood covering the upper run of a conveyor belt forming the conveyor, and provided with an inlet and an outlet to convey a gaseous temperatu recontrolling medium.

7. Apparatus according to claim 2, wherein the device for conveying a temperature-controlling medium is in the form of a hollow body arranged below the upper run of a conveyor belt forming the conveyor and between the supporting members, for passing through a liquid and/or gaseous medium.

8. Apparatus according to claim 1, wherein the breaking means comprises a roller arranged above the upper run of a conveyor belt forming the conveyor.

9. Apparatus according to claim 8, wherein the roller has projections on its outer periphery, with which a pattern can be impressed in the layer of compressed material.

10. Apparatus according to claim 1, wherein the compressing means comprise a backing plate arranged below the upper run of a conveyor belt forming the conveyor and, above the upper run, a pressure plate which can be raised and lowered and which has a vibrator.

11. Apparatus according to claim 10, wherein the pressure plate is designed for movement in the same direction as and in the opposite direction to the upper run of the conveyor belt.

12. Apparatus according to claim 10, wherein the pressure plate is designed to convey a temperaturecontrolling medium.

13. Apparatus according to claim 10, wherein the backing plate has nozzles adapted to be fed with compressed air, to maintain an air cushion between the backing plate and the underside of the upper run of the conveyor belt.

14. Apparatus according to claim 1, wherein the breaking means are constructed as a cutter which can be raised and lowered relative to the surface of the upper run of a conveyor belt forming the conveyor with a compressible stripper attached to it near its cutting edge.

15. Apparatus according to claim 10, wherein the backing plate has two guide plates which laterally bound the conveyor belt and which can be heated.

16. Apparatus according to claim 1, wherein a rotating circular brush is provided in front of the compressing means in the direction of movement of the conveyor, to spread the material evenly over the con- 

1. Apparatus for pelletizing material of low binding power or low moisture content, comprising a conveyor for transporting said material from a charging point to a discharging point, means for spreading the material to be pelletized over the conveyor to form a layer, means for compressing the material layer, and breaking means located downstream from said compressing means for dividing said layer into pellets, said compressing means and said breaking means being separately positioned along said conveyor at spaced apart points and extending at least to points intermediate said charging and discharging points.
 2. Apparatus according to claim 1, wherein a device co-operating with the conveyor is provided to convey a temperature-controlling medium.
 3. Apparatus according to claim 1, wherein the conveyor comprises a conveyor belt circulating endlessly about rollers, with supporting members arranged below the upper run and extending transversely to the direction of movement of the belt.
 4. Apparatus according to claim 1, wherein the conveyor comprises a revolving disc, with a feed point, a distributor, compressing means and a deflector arranged in front of the feed point to break up the compressed layer.
 5. Apparatus according to claim 1, wherein the compressing means is in the form of a roller arranged above the upper run of a conveyor belt, inter-acting with the belt and a supporting member and forming a nip.
 6. Apparatus according to claim 2, wherein the device for conveying a temperature-controlling medium is constructed as a hood covering the upper run of a conveyor belt forming the conveyor, and provided with an inlet and an outlet to convey a gaseous temperature-controlling medium.
 7. Apparatus according to claim 2, wherein the device for conveying a temperature-controlling medium is in the form of a hollow body arranged below the upper run of a conveyor belt forming the conveyor and between the supporting members, for passing through a liquid and/or gaseous medium.
 8. Apparatus according to claim 1, wherein the breaking means comprises a roller arranged above the upper run of a conveyor belt forming the conveyor.
 9. Apparatus according to claim 8, wherein the roller has projections on its outer periphery, with which a pattern can be impressed in the layer of compressed material.
 10. Apparatus according to claim 1, wherein the compressing means comprise a backing plate arranged below the upper run of a conveyor belt forming the conveyor and, above the upper run, a pressure plate which can be raised and lowered and which has a vibrator.
 11. Apparatus according to claim 10, wherein the pressure plate is designed for movement in the same direction as and in the opposite direction to the upper run of the conveyor belt.
 12. Apparatus according to claim 10, wherein the pressure plate is designed to convey a temperature-controlling medium.
 13. Apparatus according to claim 10, wherein the backing plate has nozzles adapted to be fed with compressed air, to maintain an air cushion between the backing plate and the underside of the upper run of the conveyor belt.
 14. Apparatus according to claim 1, wherein the breaking means are constructed as a cutter which can be raised and lowered relative to the surface of the upper run of a conveyor belt forming the conveyor with a compressible stripper attached to it near its cutting edge.
 15. Apparatus accordIng to claim 10, wherein the backing plate has two guide plates which laterally bound the conveyor belt and which can be heated.
 16. Apparatus according to claim 1, wherein a rotating circular brush is provided in front of the compressing means in the direction of movement of the conveyor, to spread the material evenly over the conveyor.
 17. Apparatus according to claim 1, wherein the compressing means comprise a rammer driven by a working medium, with a foot corresponding to the width of the conveyor, and an endless belt moving around the rammer and foot and guided by rollers.
 18. Apparatus according to claim 17, wherein the endless belt is biased towards the conveyor near and on both sides of the foot by means of rollers and springs.
 19. Apparatus according to claim 2, wherein an endless conveyor belt forming the conveyor is provided with projections on its upper surface. 